The present invention relates to a display controller for refreshing operator's visual strain, particularly caused by gazing a computer display.
There is a display controller proposed for the purpose in a Japanese patent application entitled "Character Display Device" and laid open as a Provisional Publication No. 98695/'88. In this first prior art, character data are displayed alternately at certain intervals with two complementary colors registered in a lookup table intending to reduce visual strain of the operator.
In another prior art disclosed in a Japanese patent application entitled "VDT Device", and laid open as a Provisional Publication No. 166493/'90, there are provided a color control circuit and a wrist rest for measuring operator's pulses and temperature. In this second prior art, characters are displayed with yellow color in the beginning of a VDT operation, for stimulating physical activity of the operator. According to progress of fatigue, which is measured by the pulses and temperature, the display color is controlled to change gradually from yellow to leaf green, intending to reduce operator's strain.
On the other hand, there are many offices where wall color is prepared to be different to character display color in order that operators may calm their eyes by occasionally looking the wall color.
However, even when only character display color is changed alternately into its complementary color, as disclosed in the first prior art, achromatic effect of the color stimuli is limited within a narrow area of operator's retina. So, recovery effect from fatigue caused by the color stimuli can not be obtained sufficiently.
Nor is effective to change character display color from yellow to leaf green, in such a way as proposed in the second prior art, because changing display color from yellow to leaf green has no effect to eliminate color stimuli of chromatic colors by making them achromatic with complementary colors, resulting in insufficient recovery from the fatigue caused by the color stimuli.
Effect of arranging working surroundings, such as the wall color above described, is also limited, because it is difficult to arrange the working surroundings adequately to a variety of display devices each having different character color, character size, brightness, contrast, flickering, and so on. Furthermore, it is somewhat troublesome for the operator to adjust working surroundings such as lighting or illuminations, or to look expressly a far object away from the display.